Wells occasionally need to be abandoned. Sometimes the abandonment is permanent and other times it is temporary. Abandonment usually requires an isolation device such as a bridge plug. In some abandonments the plug has cement delivered on to top it. In gas wells there are regulations for the level of sealing that is required. These standards are known as V0 or V3, for example.
While inflatables have been used in subterranean locations for a long time their use is principally focused on external casing packers mostly in open hole applications where the inflatables are extended with a material that sets up such as cement and the inflatable packer is intended to stay in position permanently. One concern in the design of inflatables is the available grip against differential pressure. Another concern is to avoid trapping fluids when inflating. This issue is often addressed with a sealing element that has overlapping metallic rib segments embedded in the opposed ends of the sealing element so that the unreinforced middle section of the sealing element comes out first to displace well fluids as the inflatable continues to enlarge under increasing inflate fluid pressure. In an effort to enhance the ability of the inflatable to grip, the sealing and anchoring functions have been assumed by discrete inflatables that seal and anchor respectively. One such design, U.S. Pat. No. 6,009,951, is shown in the context of a permanent packer inflated with cement with separate inflatables, as shown in that patent, 40 and 42 for sealing and anchoring respectively. The anchor portion 42, in that patent, has one or more stiffener rings 60. The sealing element 40 has embedded ribs at each end to encourage the middle of the sealing element to come out first so that well fluids can be displaced as the seal 40 is inflated into position. While this design works for a permanent external casing packer it does not achieve the sealing degree needed for gases per the available standards that are applied particularly to very deep wells in the order of 10,000 meters or deeper.
The present invention provides discrete anchor and sealing inflatables but disposes overlapping ribs under the annular sealing element in the seal portion of the assembly. The anchor portion includes one or more stiffeners and the inflatable elements have valving systems that permit deflation so that the well can be put into service after the bridge plug and any associated cement are removed. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.